Research On Fragmentation Characteristics Of Packaged Structure Projectile In High-velocity Impact

Frequency of space activities increasing in recent years,the threat of orbit debris to spacecraft increases gradually,which leads to a complicated structure and shape of orbit debris.During the explosion and disintegration of spacecrafts,it’s probable that fragments composed of various materials collide in hypervelocity,eventually forming a package structure,which changes the hypervelocity impact behavior of orbit debris.At present,researches on hypervelocity impact of orbit debris have ignored or limitedly considered the shape factors of orbit debris,while the special fragmentation effect brought by the package structure cannot be ignored.In this paper,several packaged projectiles are designed to simulate the special orbit debris,facilitating the research of the effect of the packaged structure.The combination of theoretical analysis and simulation experiments is used to study the crushing and damage characteristics of the packaged projectile in different impact conditions.The theoretical analysis part of this paper mainly studies the mechanical behavior of projectile fragments before breaking and the kinematic behavior of fragments after breaking.Through some assumptions and idealized models,the force of the jacket and core filler during penetrating the metal plate is analyzed.The equations of energy,the axial velocity and radial velocity of the fragment are obtained based on the energy law,which can be used on the packaged projectile.Finally,a fragmentation parameter calculation model is obtained,which reflects the fragmentation characteristics of the projectile under specific impact conditions.In the term of simulation analysis,the structural parameters which affect the crushing characteristics of the projectile are analyzed based on the theoretical analysis results.The projectile parameters mainly include the structural parameters of the notch and the number of jacket segments.By designing projectiles with different structural parameters,analyzing the axial residual velocity,radial diffusion velocity,and damage results of the protective structure of various projectiles in the simulation results,the rule of the influence of structural parameters on the crushing characteristics of the projectile is obtained.The design parameters of the shield are extracted into three aspects: the thickness,spacing and material of each layer of plates.By adjusting the thickness of each plate to simulate the high-velocity impact of the packaged projectile,the influence of plates thickness on the crushing characteristics of the projectile was obtained.The protective effect of flexible materials represented by Kevlar on packaged projectiles was studied,and Kevlar was applied to the multi-layer plate shield.And the protection design scheme suitable for the protection of packaged projectiles was obtained by adjusting the board spacing.